Microstructure and Transport Properties of Compaction-Modified In Situ Fe/MgB2 Wires

This study has shown the effect of excessive mechanical deformation by pressing and consecutive heat treatment, respectively, on the microstructure and transport properties of mono-core sintered in situ Fe/MgB2 wires. These wires were pressed into short tapes under 1 GPa uni-axial pressure. Transport properties like critical temperature, transition width and engineering critical current density of the same samples were determined before and after pressing and after annealing. Phase formation and grain size of the samples were studied with XRD. The SEM analysis indicated that the mechanical deformation reduced initial voids to a large extent but caused cracks, increased the number of grain boundaries and introduced weak links. The subsequent heat treatment on the pressed samples improved the microstructure and the grain connectivity. Possibility of a final densification of the reacted in situ wires was discussed in terms of transport properties.